1. Field of the Invention
The present invention relates to a flip-chip mounted semiconductor device and a manufacturing method thereof, in particular relates to a semiconductor device of which layer filling a gap between a semiconductor element and a printed wiring board consists of anisotropic conductive film and resin and a manufacturing method thereof.
2. Description of the Related Art
Recent advancements in downsizing, thinning or lightweight and high performance of various electronic instruments, in particular of information instruments such as personal computers and portable telephones is remarkable. In particular, in semiconductor devices, further integration and higher performance are demanded. As a result, further or, advancements are demanded in high-density mounting technology. Among them is the bare-chip mounting method.
In flip-chip mounting that is a typical mounting method, a bare chip is mounted through a protruded electrode (bump electrode) on a printed wiring board. After flip-chip mounting, in a gap generated between a semiconductor chip and the printed wiring board, filler such as resin is filled, followed by bonding with a motherboard to implement packaging.
With reference to FIG. 8, a semiconductor device due to an existing flip-chip mounting method will be explained. On a conductor pad electrode 2 of a printed wiring board 1, a metal bump 3 is formed. On a prescribed position of the printed wiring board thereon a semiconductor element 7 is mounted, as a filling layer, an anisotropic conductive film (ACF) 4 including a conductive particle 4a is stuck. Thereafter, a rear face of the semiconductor element 7 provided with an aluminum electrode 6 is pressurized and heated to electrically and mechanically bond the semiconductor element 7 and the printed wiring board 1, thereby assembling a semiconductor device.
The existing semiconductor device in which anisotropic conductive film alone is used is remarkably poor in reliability, particularly poor in adherence due to being hygroscopic. Accordingly, there are problems that bonding failure occurs between the semiconductor element and the printed wiring board.
Even in using, instead of the anisotropic conductive film, anisotropic conductive paste (ACP), there are similar problems.
Further, usually, after flip-chip mounting of a semiconductor element, solder reflow step is carried out to solder mount a chip component or to form solder bump for external terminals. Due to heat acting during the reflow step, a board becomes liable to warp. Due to warping of the board, a soldered portion of the board tends to peel. Accordingly, after the reflow, the electrode 6 of the semiconductor element 7 and the conductor pad electrode 2 of the printed wiring board 1 are peeled or being peeled therebetween to result in an increase of connection resistance.
As mentioned above, in the existing filling layer consisting only of the anisotropic conductive film 4, due to being hygroscopic, bonding failure between the semiconductor element 7 and the printed wiring board 1 is caused or after the reflow, the connection resistance between the semiconductor element 7 and the printed wiring board 1 increases.
The present invention is made to solve the aforementioned existing problems. That is, the object of the present invention is to provide a semiconductor device of which bonding reliability between a semiconductor element and a printed wiring board is improved and a manufacturing method thereof.
A semiconductor device of the present invention comprises a printed wiring board and a semiconductor element mounted through a protrusion and a filling layer on the printed wiring board, the filling layer consisting of resin and anisotropic conductive member.
In the present semiconductor device, between the printed wiring board and the semiconductor element, the anisotropic conductive member is formed in frame, the resin being filled in the frame.
In the present invention, though the anisotropic conductive member is formed so as to completely surround the resin, the frame-shaped anisotropic conductive member may be partly truncated.
A manufacturing method of semiconductor devices, one mode of the present invention, comprises the steps of forming a protrusion on an area where a semiconductor element is formed on the printed wiring board; forming anisotropic conductive member in frame on the semiconductor element area thereon the protrusion is formed; filling resin in the frame; mounting a semiconductor element through the protrusion, the anisotropic conductive member and the resin; curing the anisotropic conductive member; and curing the resin.
A manufacturing method of semiconductor devices, another mode of the present invention, comprises the steps of forming a protrusion on an area where a semiconductor element is formed on a printed wiring board; forming anisotropic conductive member in frame on the semiconductor element area thereon the protrusion is formed; filling resin in the frame; mounting a semiconductor element through the protrusion, the anisotropic conductive member and the resin; and curing the anisotropic conductive member and the resin.